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In this paper, a new zero voltage zero current transition (ZVZCT) boost DC–DC converter using a coupled inductor is proposed. This topology provides the main switch ZVZCT for the turn-on and zero voltage switching (ZVS) for the turn-off. Moreover, the auxiliary switch turns on at zero current switching (ZCS) and turns off at ZVS. The main diode turns on with ZVT and turns off with ZCS, and other diodes also operate under soft-switching conditions. Besides, due to the coupling effect, the proposed converter improves efficiency additionally since resonant energy in the resonance tank could be transferred to the output, and the circulating current can be limited as well. The soft-switching can be realized in almost all the load rang. In this design, there always exist energy releasing circuits to conduct magnetic flux leakage currents, such that the surge currents are eliminated and switch current stress can be accordingly reduced. All the devices resonate in a unique direction within less than half of a resonance period, so power losses with respect to the resonance can be decreased. In this paper, the converter design and operation principles of the converter are given. It also has been verified by a 1-kW experimental prototype with switching frequency of 100 kHz, and the related experimental results are presented. [ABSTRACT FROM PUBLISHER]

Pulse-width-modulated (PWM) converters have been widely applied for power processing, and they are typically the stems of other types of converters, such as quasi-resonant, Z-source, and switched-inductor hybrid converters. Development of PWM converters has been spanning over a century, starting from the buck converter. The well-known PWM converters include buck, boost, buck–boost, Ćuk, single ended primary inductive converter (SEPIC), zeta, Z-source, quasi-Z source, etc. Many attempts have been proposed to develop these converters based mostly on canonical cell concepts and by introducing extra LC filters to the cells. This paper presents an enhancement to the layer and graft schemes by introducing the ideas of dc voltage/current offsetting, capacitor/inductor component splitting, diode grafting, and inverse operation of PWM converters. The PWM converters, which can be operated in continuous conduction mode (CCM) or discontinuous conduction mode (DCM), therefore can be synthesized systematically according to decoded transfer gains. Decoding and synthesizing PWM converters uniquely bridge transfer gains to converter topologies and provide readers a comprehensive understanding of PWM-converter evolution from the original converter, the buck converter. Additionally, in this paper, the Ćuk, SEPIC, and zeta converters all with the same transfer gain of $D/(1 - D)$ are proved to be equivalent to the buck–boost converter with an extra LC filter. For further illustrating the proposed approaches, various types of Z-source converters, switched-capacitor/switched-inductor hybrid converters, and a single-stage interleaved converter are reviewed, and new PWM converters are developed. [ABSTRACT FROM AUTHOR]

This paper presents a deadbeat-based method for the single-inductor multiple-input multiple-output (SI-MIMO) dc–dc converter. By solving the cross regulation problem of the SI-MIMO dc–dc converter, the proposed method is capable of achieving the input current regulation (ICR) and the output voltage regulation (OVR) simultaneously. Moreover, the output current observers are adopted to replace the output current sensors, which are required by the conventional model based methods for dc–dc converters. The proposed control approaches including ICR and OVR are discussed in detail. To verify the effectiveness of the proposed deadbeat-based method, simulation runs and experiments are conducted on the single-inductor dual-input dual-output buck converter simulation platform and hardware prototype, respectively. The simulation and experimental results are analyzed in detail, and the comparison with the previous works is conducted. [ABSTRACT FROM AUTHOR]

This paper presents a dynamic power flow management system for a solar photovoltaic (PV) system employing a single-stage single-inductor-based dual-input/output dc–dc converter feeding standalone dc loads backed up by a rechargeable battery. A time-sharing voltage-mode control scheme has been proposed for power flow management between solar PV, a battery, and a standalone dc load, and it also maintains a constant dc load voltage and performs maximum power point tracking operation of solar PV. The implementation of the control scheme has been described in detail. The steady-state performance of the single-stage converter has been explained with the relevant analytical expressions derived along with the characteristics. A state-space average model was developed for simulating the transient behavior and validating the working of the system for step changes in the input solar PV power and the dc loads. A hardware prototype of the proposed system has been fabricated, and the proposed controller has been implemented using the dSPACE DS1103 real-time interface board. The working of the proposed scheme for different levels of input solar insolation and dc load power demand has been satisfactorily demonstrated, and the corresponding results are also provided. [ABSTRACT FROM AUTHOR]

A hybrid boosting converter (HBC) with collective advantages of regulation capability from its boost structure and gain enhancement from its voltage multiplier structure is proposed in this paper. The new converter incorporates a bipolar voltage multiplier, featuring symmetrical configuration, single inductor and single switch, high gain capability with wide regulation range, low component stress, small output ripple and flexible extension, which make it suitable for front-end PV system and some other renewable energy applications. The operation principal, component stress, and voltage ripple are analyzed in this paper. Performance comparison and evaluation with a number of previous single-switch single-inductor converters are provided. A 200-W 35 to 380 V second-order HBC prototype was built with peak efficiency at 95.44%. The experimental results confirms the feasibility of the proposed converter. [ABSTRACT FROM PUBLISHER]

In order to obtain a high step-up voltage gain, high-efficiency converter, this paper proposed a dual switches dc/dc converter with three-winding-coupled inductor and charge pump. The proposed converter composed of dual switches structure, three-winding-coupled inductor, and charge pump. This combination facilitates realization of high step-up voltage gain with a low voltage/current stress on the power switches. Meanwhile, the voltage across the diodes is low and the diode reverse-recovery problem is alleviated by the leakage inductance of the three-winding-coupled inductor. Taking all these into consideration, the efficiency can be high. This paper illustrated the operation principle of the proposed converter; discussed the effect of leakage inductance on voltage gain; the conditions of zero current shutting off of the diodes are illustrated; the voltage and current stress of the power devices are shown; a comparison between the performance of the proposed converter and previous high step-up converters was conducted. Finally, a prototype rated at 500 W has been established, and the experimental results verify the correctness of the analysis. [ABSTRACT FROM AUTHOR]

This paper introduces a SEPIC-derived bidirectional dc–dc converter. The proposed converter utilizes tapped inductor and charge pump techniques to achieve steep voltage conversion ratio and an active lossless regenerative snubber to attain lossless switching and high efficiency. The paper presents the principle of operation, steady-state analyses, and experimental results obtained from a 400-W, 48-V/380-V prototype. The efficiency of the proposed topology is demonstrated to peak at 96.4% for boost mode and 95.0% for buck mode. [ABSTRACT FROM AUTHOR]

Traditionally, switched-capacitor (SC) converters have suffered from high transient currents, which limit both the efficiency and power density of such converters. Soft-charging operation can be employed to eliminate the current transients and greatly improve the power density of SC converters. In this approach, a second-stage magnetic converter is cascaded with the SC stage to act as a controlled current load. Another approach is to use resonant SC converters with zero-current switching. This paper shows that resonant and soft-charging operations of SC converters are closely related, and a technique will be proposed, which achieves either operation by adding a single inductor to existing SC topologies. In addition, since most preexisting resonant or soft-charging SC converters were devised in an ad-hoc manner, this paper formulates an analytical method that can determine whether an existing conventional SC converter topology is compatible with the proposed approach. A number of common SC topologies are analyzed, including Dickson, series-parallel, ladder, Fibonacci, and doubler configurations. Through comparison to simulated results, as well as experimental work, the proposed method is validated and a family of high-performance SC converters is obtained. [ABSTRACT FROM AUTHOR]

This paper introduces a SEPIC-derived converter suited for alternative energy generation applications. The proposed converter utilizes tapped inductor and charge pump techniques to achieve high step-up gain and a passive regenerative snubber to attain high efficiency. Compared with earlier counterparts, the proposed converter has the advantage of continuous input current, which can be helpful in attaining accurate tracking of maximum power point of solar panels. The paper presents principle of operation, theoretical analysis, and design guidelines. Theoretical expectations were confirmed by simulation and experimental results. [ABSTRACT FROM AUTHOR]

One limitation of many battery charge equalizers is their slow equalization speed, especially when there are a large number of batteries in the series-string in high-voltage and high-power applications. This paper presents a new architecture for battery charge equalization. In this architecture, independent equalizers are placed in different layers and all the layers can equalize the corresponding batteries simultaneously, thus reducing equalization time by 50%. We explore the operation, performance characteristics, and the design of the architecture. Both simulation and experimental results are presented to validate the analysis in this paper. [ABSTRACT FROM AUTHOR]

High step-up voltage gain dc/dc converters are widely used in renewable energy power generation, uninterruptible power system, etc. In order to avoid the influence of leakage inductor in coupled inductors based converters, switched-inductor boost converter (SL-boost), switched-capacitor boost converter (SC-boost) and active-network converter (ANC) have been developed. With the transition in series and parallel connection of the inductors and capacitors, high step-up voltage conversion ratio can be achieved. This paper discusses the characteristics of the switched inductor and switched-capacitor cell; makes some comparisons between the ANC and boost converter. Based on the aforementioned analysis, this paper proposed the multicell switched-inductor/ switched-capacitor combined active network converters (MSL/SC-ANC). The proposed converters combine the advantages of SL/SC unit and active-network structure. Compared with previous high step-up converters, the novel converter provides a higher voltage conversion ratio with a lower voltage/current stress on the power devices, moreover, the structure of proposed SL/SC-ANC is very flexible, which means the quantity of SL and SC cells can be adjusted according to required voltage gain. A 20 times gain prototype is designed as an example to show the design procedure. Theoretical analysis and experimental results are presented to demonstrate the feature of the proposed converter. [ABSTRACT FROM AUTHOR]

This paper presents a high-frequency, digitally controlled high-brightness LED driver for automotive applications with fast dimming capabilities. The power converter is based on the magnetically coupled Ćuk topology and employs a single, off-the-shelf SMT mutual inductor. The proposed digital control technique exploits the inherent stabilizing effect of magnetic coupling, and combines it with a dedicated duty cycle feedforward technique for step-reference response enhancement during the dimming operation. No direct sensing of the LED string current is performed, bypassing the disadvantage of the Ćuk topology of having an inverted output polarity. Furthermore, the magnetically coupled Ćuk topology is a single-switch solution and it provides inherent filtering of the input and output currents without introducing the additional magnetic elements, strongly reducing the total required capacitance and maintaining the small form-factor required in the automotive environment. This paper discusses the theoretical and practical development of the proposed controller. Experimental tests on a 40-W, 1-A, 500-kHz prototype indicate a 0- to 1-A current rise time in the tens of microseconds time frame with excellent damping characteristics and regulation accuracy. [ABSTRACT FROM AUTHOR]

A synthesis methodology for developing a set of very high step-up dc–dc converters is presented and discussed in this paper. The proposed method makes use of a boost converter as basic topology in which three step-up techniques are combined and incorporated. The studied techniques are the switched capacitors voltage multipliers (VM), the diode VMs, and the coupled-inductors. With the proposed methodology, many well-known converters are identified and two novel converters are proposed. In addition to a detailed analysis of the synthesis of each topology, a comparative analysis among of some important converters is presented. This comparison involves aspects such as voltage gain, voltage stress, component stress factor, component count, and relative cost. By means of these comparisons, the main characteristics and constraints of the analyzed converters are identified. Results from 250 W prototypes, designed according to photovoltaic ac-module specifications, are obtained experimentally to validate the theoretical analyses and point out advantages and limitations of each converter. The results demonstrate that the combination of the three studied techniques provides the best trend off on the comparative analysis carried out in this work. [ABSTRACT FROM PUBLISHER]

In this paper, a nonisolated dc−ac inverter topology, which enables a true single-stage direct conversion from a single dc input supply to multiple ac output power sources by using only one inductor in the power stage, is proposed. Compared with the conventional multiple-output parallel half-bridge or full-bridge inverters, the proposed single-stage single-inductor multiple-output (SIMO) inverter topology achieves a smaller number of inductors and power switches, high power density, scalability to multiple ac outputs, and independent power controllability for each ac output. A useful application of the proposed SIMO inverter is to drive an array of transmitting coils simultaneously for wireless power transfer applications. An experimental prototype has been developed to demonstrate the effectiveness of a single-inductor three-output boost-derived inverter without cross regulation. Experimental results show that precise and independent peak voltage regulation of each individual sinusoidal ac output is attainable with the proposed SIMO inverter. [ABSTRACT FROM AUTHOR]

A novel high-conversion-ratio bidirectional dc–dc converter with coupled inductor is proposed in this paper. Compared with the bidirectional converters based on coupled inductor, this new topology can realize a higher step-up voltage gain and lower step-down voltage gain with a lower turn ratio in an appropriate duty cycle. In proposed converter, the windings of the coupled inductor are reversely connected to transfer energy from high voltage source or low voltage source. Then, a clamp capacitor is applied to reduce voltage stress on main switch; therefore, the conduction loss of the main switches can be reduced by using a low resistance switch, and the clamp capacitor can also recycle the energy of the leakage inductor in coupled inductor. Besides, the soft-switching technique is used to achieve zero voltage switching, so the efficiency can be further improved. The main circuit and its steady-state operating principle are analyzed in detail. Finally, a 25–200 V 200 W bidirectional dc–dc converter is implemented to verify its performance. [ABSTRACT FROM AUTHOR]

A CLTCL resonant dc-dc converter is proposed in this paper. Through the dual-transformer architecture, the resonant characteristic of the converter alters and contributes to a wide input voltage range and a greatly broadened output voltage range from zero to the nominal. The transformer leakage inductors also participate in the resonating process, which eliminates their side effects on the conversion performance. Moreover, a simple and effective design method for converters with multiple resonant components is used to guide the resonant parameter design with the assistance of the MATLAB program. Soft switching for both turn-on and turn-off processes of all the inverter and rectifier switches is acquired, and the proposed converter, therefore, achieves lower switching losses among a wide load scope. In the end, a 1-kW prototype with a peak efficiency of 97.3% is fabricated in the laboratory to verify the working principle and design effect of the CLTCL converter. [ABSTRACT FROM PUBLISHER]

This paper presents a dc–dc boost converter topology for low input and high output voltage applications, such as photovoltaic systems, fuel cell systems, high-intensity discharge lamp, and electric vehicles. The suggested configuration consists of a three-winding coupled-inductor, a single switch and two hybrid voltage multiplier cells. Furthermore, two independent hybrid voltage multiplier cells are in parallel when the single switch S is turned on, and they are in series when the switch S is turned off. So, the advantages of the proposed converter structure are summarized as follows: 1) A coupled inductor with three windings is introduced in the presented converter structure. The two secondary windings of the coupled inductor are, respectively, used to form a hybrid multiplier cell on the one hand, on the other hand, it increases the control freedom of the voltage gain, enhances the utility rate of magnetic core and power density, and reduces the stress of power components to provide a stable constant dc output voltage. 2) The two hybrid multiplier cells can absorb synchronously the energy of stray inductance, which not only reduces the current stress of corresponding diodes, but also greatly alleviates the spike voltage of the main switch, which improves the efficiency. 3) The two hybrid multiplier cells are connected in series to supply power energy for the load, so the voltage gain is extended greatly due to this particular structure. Thus, low-voltage low-conduction-loss devices can be selected and the reverse-recovery currents within the diodes are inhibited. The operating principles and the steady state analyses of the proposed converter are discussed in detail. Finally, a test prototype has been implemented in the laboratory, and the simulated and experimental results show satisfactory agreement with the theoretical analysis. [ABSTRACT FROM AUTHOR]

A new high step-up interleaved converter is proposed in this paper. This new high step-up converter utilizes the interleaved boost converter to be in series connection with the voltage-double module. The secondary sides of the coupled inductors are in interleaved series connection and shared by two voltage-double modules to accomplish the interleaved energy storage. Then, the input voltage, coupled-inductors, and multiplier capacitors are in series connection with the output to achieve the purpose of high voltage gain. The proposed circuit can be operated at a lower duty cycle to achieve high voltage gain by adjusting the turn ratio of the coupled inductors. The proposed circuit has less elements and the voltage stress of the switches and diodes can be decreased to reduce the cost. The conduction loss can be reduced and the efficiency can be increased when the switch with lower conduction resistance is applied. Finally, a prototype circuit of a 400 W high step-up converter with input voltage of 24 V and output voltage of 400 V is realized. Through simulation and experiments, the validity and property of the proposed converter can be verified. [ABSTRACT FROM PUBLISHER]

DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques. [ABSTRACT FROM AUTHOR]

The modular multilevel converter is a well-known modular multilevel topology. This paper proposes a novel branch inductor coupling and compares it to the center-tapped inductor and the standard noncoupled inductor topology. The proposed coupling has a significant influence on the inductor and converter dimensioning. Its properties make it especially well suited for use in single-to-three-phase ac/ac modular multilevel convert-er applications. [ABSTRACT FROM PUBLISHER]

The boost converter with a voltage multiplier cell allows the static gain extension by means of the switching capacitor technique, reducing the duty cycle needed to achieve the same voltage gain when compared to the conventional boost converter. However, the modeling of this converter is complex and requires the use of advanced techniques due to the resonant inductor. Thus, this paper aims to present a reduced-order model of this converter without the resonant energy exchange between the capacitors, so that the state-space averaging technique can be applied assuming small ripple in the state variables. In addition, this paper presents the design of a control system for the boost converter with a voltage multiplier cell. The adopted strategy employs an inner loop to control the input current and an outer loop for the output voltage regulation. Extensive analysis based on simulations and an experimental prototype demonstrate that the proposed modeling, although simplified, is sufficient for an adequate control system design, ensuring good voltage regulation, and fast transient responses. [ABSTRACT FROM PUBLISHER]

This paper proposes a converter topology dedicated to the interconnection between low voltage and high voltage networks or power sources. This topology uses the interleaving principle whose advantages are well known at this point. Its originality stems from the implementation of an isolating intercell transformer (ICT) that provides isolation, filtering, and intercell coupling through a single magnetic stage. The first section of this paper presents two ways to build bidirectional multicell converters, based on classic buck (or boost) cells on one hand, and buck-boost cells on the other. From the nonisolated versions of these two families, the synthesis of isolated versions is achieved by introducing classic two-winding coupled-inductors or transformers. A nonbidirectional isolated ICT version derived from the buck-boost family, the multicell ICT flyback converter, has already been studied and tested. Therefore, the second section describes the isolated multicell ICT converter derived from the buck (or boost) family and constitutes the main contribution of this paper. Its very interesting features regarding high step-up ratio requirements are emphasized, particularly by considering some limitations of the ICT flyback converter. Finally, a 10-kW test bench is presented. This test bench includes eight cells and an ICT created with separated transformers, making it possible to validate converter operations under realistic power conditions. [ABSTRACT FROM AUTHOR]

Switched boost inverter (SBI) is a single-stage power converter derived from Inverse Watkins Johnson topology. Unlike the traditional buck-type voltage source inverter (VSI), the SBI can produce an ac output voltage that is either greater or less than the available dc input voltage. Also, the SBI exhibits better electromagnetic interference noise immunity when compared to the VSI, which enables compact design of the power converter. Another advantage of SBI is that it can supply both dc and ac loads simultaneously from a single dc input. These features make the SBI suitable for dc nanogrid applications. In this paper, the SBI is proposed as a power electronic interface in dc nanogrid. The structure and advantages of the proposed SBI-based nanogrid are discussed in detail. This paper also presents a dq synchronous-reference-frame-based controller for SBI, which regulates both dc and ac bus voltages of the nanogrid to their respective reference values under steady state as well as under dynamic load variation in the nanogrid. The control system of SBI has been experimentally validated using a 0.5-kW laboratory prototype of the SBI supplying both dc and ac loads simultaneously, and the relevant experimental results are given in this paper. The low cross regulation and the dynamic performance of the control system have also been verified experimentally for a 20% step change in either dc or ac load of SBI. These experimental results confirm the suitability of the SBI and its closed-loop control strategy for dc nanogrid applications. [ABSTRACT FROM AUTHOR]

A new three-level dc/dc converter is proposed in this paper. The outstanding features of this converter are that it operates with zero-voltage-switching (ZVS) from full-load to near no-load conditions with hardly any circulating freewheeling primary current due to its novel structure. Since the converter has little primary circulating current and its switches are exposed to only half of the input voltage, it has high efficiency even under light loads. In this paper, the new converter is introduced, its basic operating principles are explained, its modes of operation and its steady-state characteristics are discussed in detail as is its design, and experimental results obtained from a prototype converter that confirm its feasibility are presented. [ABSTRACT FROM AUTHOR]

To overcome the traditional buck converter, which is difficult to achieve a high step-down gain with an appropriate duty cycle, a coupled-inductor-based step-down converter, named ultrahigh step-down converter, is proposed by Hwu et al. [11]. As compared with the buck converter, the ultrahigh step-down converter can achieve a much higher step-down gain, which can be determined by not only the duty cycle but also the turns ratio of the coupled inductor. However, the ultrahigh step-down converter is designed at a fixed input voltage of 48 V. In the telecommunication applications, the high dc bus voltage varies in a wide range, not kept at a fixed nominal voltage of 48 V. The experimental results show that as the input voltage increases, the efficiency of the ultrahigh step-down converter decreases. Therefore, in this paper, an improved ultrahigh step-down converter with a wide input voltage range is presented. According to the topology exchange, the voltage gain can be changed to a suitable one when the input voltage changes. By doing so, as compared with the ultrahigh step-down converter [11], the duty cycle of the proposed converter can be extended, and hence the efficiencies of the proposed converter can be improved. The proposed converter is verified by a wide input voltage (18–54 V), with an output voltage of 1.2 V and a rated output current of 10 A. [ABSTRACT FROM AUTHOR]

This paper presents a new single-phase switched-coupled-inductor dc–ac inverter featuring higher voltage gain than the existing single-phase qZ-source and semi-Z-source inverters. Similar to the single-phase qZ-source and semi-Z-source inverters, the proposed inverter also has common grounds between the dc input and ac output voltages, which is beneficial especially for photovoltaic inverter systems. The inverter volume and maximum current flowing can be reduced significantly through the coupling of all inductors. A theoretical analysis of the proposed inverter is described and a 280-W experimental prototype is built to verify the performance of the inverter. [ABSTRACT FROM AUTHOR]

This paper introduces the design procedure for a class of bidirectional zero fundamental ripple or zero first-order ripple (ZFR) dc–dc converters. ZFR topologies eliminate the first-order switching ripples by utilizing a coupled inductor. As a result, these converters require smaller inductive and capacitive filtering elements. After introducing the modes of operation, the average model of a ZFR converter is derived. Using this model, a scheme for optimal design of the damping circuitry is introduced. Also, the overall design procedure for a ZFR converter is introduced using an example. The designed ZFR converter is experimentally evaluated to demonstrate the effectiveness of the design procedure. [ABSTRACT FROM AUTHOR]

Following the recently proposed $\theta$ -converter that reduces voltage ripples, leakage currents, and total capacitance required in a single-phase converter, this paper further improves the $\theta$ -converter by reducing the current stress of the neutral inductor, by relocating it to the dc side without affecting the other functions of the $\theta$-converter. Based on the average circuit model of the proposed converter, it is found that the current flowing through the neutral inductor can be reduced by at least three times, and hence, the size of the inductor can be reduced by at least nine times. How to operate the converter to achieve the reduction of the current stress is discussed in detail. Moreover, the selection criteria on the neutral inductor and other passive components used in the proposed converter are discussed in order to minimize their usage. Intensive experimental results are presented to demonstrate that the proposed converter can indeed reduce the current-stress while the other functions of the $\theta$-converter are not affected. [ABSTRACT FROM AUTHOR]

This paper proposes a new 48-V dc-fed dimmable LED driver based on a resonant-switched-capacitor topology (RSCT), where the analog-based dimming feature is accomplished by means of a variable inductor (VI). The proposed topology is based on the classic RSCT step-up double mode converter and it provides a simple and cost-effective solution while guaranteeing a wide dimming range. In order to implement an analog-based dimming, the control of the dc current in the LED lamp is required. This technique proposes to replace the resonant inductor by a VI, which will control the rms value of the resonant current, and, therefore, the mean value of the LED lamp current. In order to evaluate the feasibility and performance of this method, a 22-W LED lamp and driver prototypes were built. The most relevant experimental results are presented and briefly described. [ABSTRACT FROM AUTHOR]

The series resonant soft-switching topology is widely used in high-density DCX products due to its zero switching loss. But, the conventional series resonant converter is a dual end topology, which results in complex circuit structure and high cost. In order to simplify the resonant DCX topology and reduce the cost, a novel resonant cell named input current fed (ICF) cell is proposed in this paper, which can be applied to single-ended forward topologies. The zero-voltage-switching (ZVS) on and quasi-zero-current-switching (ZCS) off for switch are both achieved. According to the duality theory of circuit, another output current sink cell is derived. Based on the proposed ZVZCS ICF cell, two cells are interleaved to construct several dual end cells, which can be extended to push–pull, full bridge, half bridge, and other dual end topologies. Based on these cells, a new family of ZVZCS resonant DCX is derived, which are suitable for high-frequency and high-efficiency applications with various power levels. The operating principle and characteristics of the cells and topologies are verified by simulations and experimental results. [ABSTRACT FROM AUTHOR]

Many high-power converter systems are often connected to the medium-voltage network using a step-up transformer. In such systems, the converter-side windings of the transformer can be configured as an open end, and multilevel voltage waveforms can be achieved by feeding these open-end windings from both ends using the two-level dual converter. An $LCL$ filter with separate converter-side inductors for each of the converter is commonly used to attenuate the undesirable harmonic frequency components in the grid current. The magnetic integration of the converter-side inductors is presented in this paper, where the flux in the common part of the magnetic core is completely canceled out. As a result, the size of the magnetic component can be significantly reduced. A multiobjective design optimization is presented, where the energy loss and the volume are optimized. The optimization process takes into account the yearly load profile and the energy loss is minimized, rather than minimizing the losses at a specific operating point. The size reduction achieved by the proposed inductor is demonstrated through a comparative evaluation. Finally, the analysis is supported through simulations and experimental results. [ABSTRACT FROM AUTHOR]

The presence of an inductor during actuation of a piezoelectric transformer (PT) is a problem that has been investigated for many years. An inductorless driving topology to solve the inductor problem is proposed in this paper. This topology consists of a driver circuit and a pure piezoelectric matching network between the circuit and PT. The driver circuit is constructed to provide a specially designed waveform. The Fourier spectrum of the waveform presents dominant fundamental and third harmonics, with higher harmonics controlled to negligible levels. The third harmonic component is eliminated by a piezoelectric filter (PF), which is a component of the piezoelectric matching network. Another component is a piezoelectric inductor used to compensate for the capacitances of the PT and PF. An experimental setup is constructed to verify the performance of the driving topology. A total efficiency of 76.3% with an input power of 14.5 W is achieved when the whole driving system is considered. Although its performance is not exactly ideal, this topology is a highlight of investigations of the inductorless actuation of PTs. The proposed circuit and pure piezoelectric matching network indicate potential improvements in the performance and miniaturization of PT-based converters. [ABSTRACT FROM PUBLISHER]

This paper proposes a high-performance transformerless single-stage high step-up ac–dc matrix converter based on Cockcroft–Walton (CW) voltage multiplier. Deploying a four-bidirectional-switch matrix converter between the ac source and CW circuit, the proposed converter provides high quality of line conditions, adjustable output voltage, and low output ripple. The matrix converter is operated with two independent frequencies. One of which is associated with power factor correction (PFC) control, and the other is used to set the output frequency of the matrix converter. Moreover, the relationship among the latter frequency, line frequency, and output ripple will be discussed. This paper adopts one-cycle control method to achieve PFC, and a commercial control IC associating with a preprogrammed complex programmable logic device is built as the system controller. The operation principle, control strategy, and design considerations of the proposed converter are all detailed in this paper. A 1.2-kV/500-W laboratory prototype of the proposed converter is built for test, measurement, and evaluation. At full-load condition, the measured power factor, the system efficiency, and the output ripple factor are 99.9%, 90.3%, and 0.3%, respectively. The experimental results demonstrate the high performance of the proposed converter and the validity for high step-up ac–dc applications. [ABSTRACT FROM PUBLISHER]

This paper presents a distributed control strategy for state-of-charge balancing between the battery modules of a reconfigurable battery energy storage system. The autonomous modules share state-of-charge information with their neighbors over a sparse communication network and cooperate to reach a balanced state of charge. The proposed control strategy provides advantages in terms of reduced communication requirements and increased modularity, over a centralized battery management system. Steady-state analysis provides bounds on the mean error and mean-squared error of the distributed average state-of-charge estimates used for autonomous balancing control. The proposed control strategy enforces module topology constraints specific to the particular reconfigurable battery implementation. The state-of-charge balancing mode current controller prevents current spikes during module topology transitions. Experimental results demonstrate the performance of the proposed control strategy for a reconfigurable energy storage system made up of four 6-V, 7-Ah lead-acid battery modules. [ABSTRACT FROM PUBLISHER]

In this paper, a novel high step-up dc–dc converter with a multicoupled inductor (MCI) and voltage multiplier is proposed for a sustainable energy system. The combinatorial employment of these components significantly extends the voltage boostability and reduces the voltage stress of the main switches. The special structure of branch cross coupling makes the two branches of current autobalance. Meanwhile, the utilization of MCIs makes the most of the magnetic core to further improve the power density. The diode reverse-recovery problem is alleviated because its current falling rate is controlled by the leakage inductance of the MCI. Moreover, the voltage spike of the main switches at their turn-off is clamped by a clamp capacitor. The interleaved operation results in the cancelation of the input current and output voltage. Next, the operating principle and performance of the converter are discussed in detail. Finally, a prototype circuit with 1-kW output power is implemented to verify the performance of the proposed converter. [ABSTRACT FROM AUTHOR]

By inserting a small inductor between the transformer center tap and the midpoint of two split output capacitors in the dual active bridge (DAB) topology, this paper proposes a modified DAB converter for wide-input applications. A hybrid phase-shift (HPS) control scheme is proposed to allow all power switches to achieve practical ZVS over the full operating range; thereby, significantly minimizing the switching losses and alleviating electromagnetic interference. Moreover, the proposed control scheme does not significantly increase the conduction losses in comparison with the extended phase-shift (EPS) control. Therefore, the modified DAB can operate efficiently. The topology derivation and description are first presented. Then, the EPS and triple phase-shift (TPS) modulations are applied, and the corresponding operating principles and characteristics, including the soft-switching, power transfer, and root-mean-square current, are investigated in detail. To achieve practical ZVS operation of all switches over full operating range, while minimizing the conduction losses, the EPS and TPS are combined, and an HPS control scheme is proposed. Finally, experimental results from a 1.4-kW converter prototype with 200–400-V input and 400-V output are presented to verify the feasibility and advantages of the converter and control. [ABSTRACT FROM AUTHOR]

Various ac/dc LED driver topologies have been proposed to meet the challenges of achieving a compact, efficient, low-cost, and robust multistring LED lighting system. These LED drivers typically employ a two-stage topology to realize the functions of ac/dc rectification and independent current control of each LED string. The choice of having two stage conversions involves additional hardware components and a more complicated controller design process. Such two-stage topologies suffer from a higher system cost, increased power loss, and large form factor. In this paper, a single-stage ac/dc single-inductor multiple-output LED driver is proposed. It uses only one single inductor and N + 1 active power switches (N being the number of LED strings) with reduced component count and smaller form factor. The proposed driver can achieve both functions of ac/dc rectification with a high power factor and precise independent current control of each individual LED string simultaneously. A prototype of an ac/dc single-inductor triple-output LED driver is constructed for verification. Experimental results corroborate that precise and independent current regulation of each individual LED string is achievable with the proposed driver. A power factor of above 0.99 and a peak efficiency of 89% at 30-W rated output power are attainable. [ABSTRACT FROM AUTHOR]

This paper presents a novel ZVZCS full-bridge DC/DC converter, which is able to process and deliver power efficiently over very wide load variations. The proposed DC/DC converter is part of a plug-in AC/DC converter used to charge the traction battery (high voltage battery) in an electric vehicle. The key challenge in this application is operation of the full-bridge converter from absolutely no-load to full-load conditions. In order to confirm reliable operation of the full-bridge converter under such wide load variations, the converter should not only operate with soft-switching from full load to no-load condition with satisfactory efficiency for the full range of operation, but also the voltage across the output diode bridge needs to be clamped to avoid any adverse voltage overshoots arising during turn-OFF of the output diodes as commonly found in regular full bridge converters. In order to achieve such stringent requirements and high reliability, the converter employs a symmetric passive near lossless auxiliary circuit to provide the reactive current for the full-bridge semiconductor switches, which guarantees zero voltage switching at turn-ON times for all load conditions. Moreover the proposed topology is based on a current driven rectifier in order to clamp the voltage of the output diode bridge and also satisfy ZVZCS operation of the converter resulting in superior efficiency for all load conditions. In this paper operation of the converter is presented in detail followed by analytical design procedure. Experimental results provided from a 3KW prototype validate the feasibility and superior performance of the proposed converter. [ABSTRACT FROM AUTHOR]

This paper deepens in the study of the recently described coupled-inductor buck-boost converter. The output voltage of this dc-dc converter can be regulated above and/or below its input voltage with high efficiency and wide bandwidth. The control of the input and/or output nonpulsating converter currents is addressed in this paper. The small-signal control-to-input/output-current transfer functions in open-loop permits the design of the respective average current-mode controllers. The combination of the input- and output-current controllers with an additional output voltage limiter loop is proposed as a method to regulate one of the currents while limiting the maximum values of the other two variables. The theoretical analyses have been validated by means of simulations and also experimentally on a 48-V 800-W purpose built-prototype. In particular, the frequency response measurements that have been carried out for a representative set of the converter operating points are in good agreement with the simulations. [ABSTRACT FROM AUTHOR]

This paper deals with a new family of high boost voltage inverters called switched-inductor quasi-Z-source inverters (SL-qZSIs). The proposed SL-qZSI is based on the well-known qZSI topology and adds only one inductor and three diodes. In comparison to the SL-ZSI, for the same input and output voltages, the proposed SL-qZSI provides continuous input current, a common ground with the dc source, reduced the passive component count, reduced voltage stress on capacitors, lower shoot-through current, and lower current stress on inductors and diodes. In addition, the proposed SL-qZSI can suppress inrush current at startup, which might destroy the devices. This paper presents the operating principles, analysis, and simulation results, and compares them with those of the SL-ZSI. To verify the performance of the proposed converter, a laboratory prototype was constructed with 48 Vdc input and an ac output line-to-line voltage of 120 Vrms. The simulation and experimental results verified that the converter has high step-up inversion ability. [ABSTRACT FROM AUTHOR]

This paper presents the analysis and design of a 30 MHz resonant SEPIC converter. With the conventional design method, tuning the amplitude and phase of the fundamental input voltage and current of the rectifier stage affect each other so that the design procedure is coupled seriously. Based on the circuit duality theory, an improved design method is proposed by redividing the resonant SEPIC topology to realize the independent tuning of the amplitude and phase. The implementation and loss analysis of the SEPIC with the new design are provided in details. Moreover, a novel structure of the PCB embedded inductors is introduced and the comparison among the discrete inductor, the planar spiral inductor and the four-layered solenoid PCB inductor is given in terms of the loss. A 15 V input, 25 W/28 V output/30 MHz SEPIC converter was built to verify the proposed design method and the benefit of the new structure of the PCB embedded inductors. The power density of the power stage is realized over 200 W/in3 and the efficiency is 82.5% at the rated output. The temperature of the proposed PCB embedded inductor is reduced from 102.6 °C (the discrete inductor) to 64.8 °C (a reduction of 37%) and the efficiency is improved 2% over the discrete solution at the full load. [ABSTRACT FROM AUTHOR]

Constant current sources are required to drive multiple color LED strings and the LED drivers that drive these LED lighting systems should provide multiple constant currents from a single dc source. In this paper, a single inductor multiple current output (SIMCO) converter that can provide N- independently controllable constant current outputs is reported. The average current in each color LED string is controlled independently by using hybrid average current mode control (HACMC). The HACMC combines the advantage of both average current mode control and charge control method. Traditional dimming approaches such as pulse width modulation and analog dimming can be incorporated in the proposed topology for color tunability and correlated color temperature control. The proposed approach uses a simple control logic, which is modular and can be scalable to N color LED lighting systems. The operation of the SIMCO converter with the HACMC is explained in detail. Simulation and experimental results with 48 V input and 12 W for $N = 3$ (RGB) color systems are presented. [ABSTRACT FROM AUTHOR]

In series-connected battery systems, typically, separate converters for intramodule balancing bidirectional connection to a load and charging from an external power source are employed. In this paper, an integrated reconfigurable converter for high-voltage series-connected battery storage systems is proposed. The main advantage of the proposed converter is that it can be reconfigured to operate in different operating modes: feeding the load from the battery system, feeding the load from a backup power source, regenerative mode, intramodule balancing mode, and charging mode. Unlike conventional systems, the proposed topology shares the semiconductor devices and an inductor among the different operating modes which makes it compact. The proposed converter exhibits redundant modes which together with a backup mode increase its reliability. Additionally, the proposed topology minimizes stress on the batteries during the charging/discharging cycles. A scaled down experimental prototype of the proposed converter is implemented for a five-module battery system to verify its viability and demonstrate all operating modes. [ABSTRACT FROM PUBLISHER]

Although a large number of typical resonant converter topologies have been developed for use in contactless power transfer applications, these topologies need to be precisely optimized to obtain maximum efficiency and maximum power transferring capacity. High-order resonant power converters with flexible designs are invariably required to develop energy-efficient and cost-effective converter systems. An ideal converter topology can contribute toward realizing efficient converter systems if it is capable of providing an optimized output that is insensitive to load variations, coupling coefficient, type of the wireless transformer used, and other operating conditions. This paper presents a new contactless power converter topology for a low-coupling (0.14) ferrite-core transformer that has low cost, small size, high efficiency, and a wide gap (20 mm). In addition, the merits and demerits of conventional converter topologies are studied herein, and results for these topologies are compared with those for the proposed converter topology. [ABSTRACT FROM PUBLISHER]

Recently, novel direct pulse width modulated (PWM) ac–ac converters using coupled inductors with switching cell structure have been introduced as an alternative to the conventional ac–ac converter topology. The converters can effectively solve the commutation problem associated with the conventional direct PWM ac–ac converters. However, the two coupled inductors used in the topology make the converters less attractive for use in practical applications. This paper proposes magnetic integration of the discrete-coupled inductors in single-phase ac–ac converters. The dc offset fluxes generated by the common-mode currents are cancelled out perfectly when the windings on the common core are appropriately arranged, resulting in ac flux only. The proposed inductor shows significant improvements over discrete-coupled inductors, in that the proposed inductor does not have an air gap, it exhibits symmetrical winding currents, and it has smaller volume with large current handling capability. The proposed inductor can handle an unlimited amount of current due to the absence of core saturation caused by the current and is well suitable for high power ac–ac conversion applications. The performance evaluation and comparison of the experimental results show that the net volume of the coupled magnetic components can be reduced by more than 50% with the proposed integration scheme. [ABSTRACT FROM PUBLISHER]

This paper revisits the switched flow graph (SFG) technique. A general and unified equivalent SFG model of a three-terminal switcher encountered in regular and tapped inductor converters operating in the continuous conduction mode is proposed. The model can be applied to most PWM topologies and facilitates construction of a complete flow graph of a given converter. The approach can be helpful in theoretical analysis and derivation of analytical expressions of converter's small-signal transfer functions. The suggested methodology extends the previously proposed SFG analysis technique and alleviates the principal difficulties involved. Furthermore, the approach is straightforward and expeditious. Application guidelines and examples are presented and compared to simulation and earlier theoretical results. [ABSTRACT FROM PUBLISHER]

Due to exponential (Moores law) scaling of advanced CMOS technologies, the challenges associated with delivering power to performance and mobile computing systems are outpacing the capabilities of conventional voltage regulator (VR) topologies. To continue to scale throughput at constant power density, the level of parallelism in microprocessor architectures is expected to increase substantially. In this paper, we present a power conversion topology to provide independent multicore regulation in the 0.8–1.4 V range from a 12-V dc bus. The topology uses a multistage ladder converter to manage power delivery to digital circuits stacked in vertical voltage domains. This approach has several advantages with regard to systems efficiency as it allows a more moderate conversion ratio of the main dc–dc converter. Moreover, the parallel converter only needs to process a fraction of the power of each core as the current can be “recycled” by adjacent cores in the stack. We develop a dynamical model for a multiple-input, multiple-output control scheme that uses a simple integral-control law, augmented with fast voltage- and current-mode feedforward. Measurement results of a discrete prototype verify the control scheme and demonstrate the potential advantages in system efficiency but also emphasize the remaining challenges in meeting stringent VR dynamic response requirements. [ABSTRACT FROM PUBLISHER]

A new method for deriving isolated buck-boost (IBB) converter with single-stage power conversion is proposed in this paper and novel IBB converters based on high-frequency bridgeless-interleaved boost rectifiers are presented. The semiconductors, conduction losses, and switching losses are reduced significantly by integrating the interleaved boost converters into the full-bridge diode-rectifier. Various high-frequency bridgeless boost rectifiers are harvested based on different types of interleaved boost converters, including the conventional boost converter and high step-up boost converters with voltage multiplier and coupled inductor. The full-bridge IBB converter with voltage multiplier is analyzed in detail. The voltage multiplier helps to enhance the voltage gain and reduce the voltage stresses of the semiconductors in the rectification circuit. Hence, a transformer with reduced turns ratio and parasitic parameters, and low-voltage rated MOSFETs and diodes with better switching and conduction performances can be applied to improve the efficiency. Moreover, optimized phase-shift modulation strategy is applied to the full-bridge IBB converter to achieve isolated buck and boost conversion. What's more, soft-switching performance of all of the active switches and diodes within the whole operating range is achieved. A 380-V output prototype is fabricated to verify the effectiveness of the proposed IBB converters and its control strategies. [ABSTRACT FROM PUBLISHER]

A novel interleaved dual buck full-bridge three-level inverter (IDBFTI) is proposed for the grid-connected system in this paper. It retains the advantages of interleaved parallel technology for inverter as follows: reducing the output ripple current and the total harmonic distortion of the output current, increasing the power density of system, and reducing the current stress and thermal stress of power devices. Besides, it can solve the problem of zero sequence circulation current (ZSCC) in interleaved inverter system by the circuit structure, and it also has the advantages of no shoot-through problem, no reverse recovery of the body diode, and three-level output. The interleaved inverter circuits share two power-frequency switches, which are resized for each specific application, and it is easier to extend the system by improving current capability of the two switches. The working principle of this system is introduced in detail, and a 2-kW experimental prototype has been established and tested. Test results verify the principle and the excellent performance of IDBFTI. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel single-phase ac–ac Z-source converter based on the Γ-structure. The proposed converter uses a coupled transformer to produce the required gain. The obtained gain can be tuned by varying the turn ratio $\gamma _\Gamma$ of the transformer within the narrow range of $1 < \gamma _\Gamma < 2$. Also, the gain factor increases with decrease of the transformer turns ratio, $\gamma _\Gamma$ . Small transformer turn ratio results in more practical topology in some voltage gains. It makes the transformer design easier and reduces construction cost. Also, in the proposed topology, the input and output voltages share the same ground. In order to avoid voltage and current spikes on the switches, a commutation strategy is proposed and safe commutation is achieved without using a snubber circuit. The operating principles and steady-state analyses are presented to verify the operational concept of the proposed topology. Also, experimental results are given to verify the validation of the proposed converter. [ABSTRACT FROM AUTHOR]